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Thermalright's HR-03 VGA cooler Q

Yes, I would say that it pushes air into the sink... I have rarely seen one doing the other way. It would be highly inefficient.
 
Hi,

I canot see any reason why it would make any difference.

All that matters is that air moves through the heatsink to keep the air around teh heatsink as cool as possible tio maximize teh temperature differential (and hence ther heat transfer) between the heatsink and the air.


In amy specific instyallation there may be reasons why pushing or pulling may yield a small improvement relative to the other. For instance, if the hoat air from the hreatsink then flows over the graphics card itself (which will be hotter still) you may get a small amount of extra cooling, but the effect is liklely to be small.

But in general ther is nor reason why either arrangement should be better than the other.




Peter

 
push ONLY.

pulling air away from the heat sink will yield almost no improvement over passive cooling. you need to push cooler air onto the heat sink to cool the metal down. pulling will remove the hot air away but will not cool the metal down resulting in higher core temperatures. just look at almost every cpu heat sink out there. they all push.
 
Originally posted by: pcy
Hi,

I canot see any reason why it would make any difference.

All that matters is that air moves through the heatsink to keep the air around teh heatsink as cool as possible tio maximize teh temperature differential (and hence ther heat transfer) between the heatsink and the air.


In amy specific instyallation there may be reasons why pushing or pulling may yield a small improvement relative to the other. For instance, if the hoat air from the hreatsink then flows over the graphics card itself (which will be hotter still) you may get a small amount of extra cooling, but the effect is liklely to be small.

But in general ther is nor reason why either arrangement should be better than the other.




Peter
Click to expand...


Here are some reasons on why... because if u look at how the sink is mounted. unless ur on a Lian Li with a inverted board, the sink will be on the bottom of the card. To pull air downwards would mean ur sucking the heat from the ram, along with the heat from everything else to cool the hot air being generated by your CPU. Hence why the guy says shows no improvement.

Pushing Up on something thats faced down is using the laws of physics to help in your cooling process. Because hot air likes to move up your pushing air up to help with the cooling.

The only time a pull config would be better then a push from my knowledge is most likely where u have plenty of cold air to be sucked in. IE. Intakes. It makes almost no sense for a outtake to be pulled. More of a push, Also pulling helps if your system is in a negitive air pressure conditions, as you will need less work on your fans hence u can devolt them to cause less noise.
 
Hi,


Originally posted by: aigomorla
Originally posted by: pcy
Hi,

I canot see any reason why it would make any difference.

All that matters is that air moves through the heatsink to keep the air around teh heatsink as cool as possible tio maximize teh temperature differential (and hence ther heat transfer) between the heatsink and the air.


In amy specific instyallation there may be reasons why pushing or pulling may yield a small improvement relative to the other. For instance, if the hoat air from the hreatsink then flows over the graphics card itself (which will be hotter still) you may get a small amount of extra cooling, but the effect is liklely to be small.

But in general ther is nor reason why either arrangement should be better than the other.




Peter
Click to expand...


Here are some reasons on why... because if u look at how the sink is mounted. unless ur on a Lian Li with a inverted board, the sink will be on the bottom of the card. To pull air downwards would mean ur sucking the heat from the ram, along with the heat from everything else to cool the hot air being generated by your CPU. Hence why the guy says shows no improvement.

Pushing Up on something thats faced down is using the laws of physics to help in your cooling process. Because hot air likes to move up your pushing air up to help with the cooling.

The only time a pull config would be better then a push from my knowledge is most likely where u have plenty of cold air to be sucked in. IE. Intakes. It makes almost no sense for a outtake to be pulled. More of a push, Also pulling helps if your system is in a negitive air pressure conditions, as you will need less work on your fans hence u can devolt them to cause less noise.
Click to expand...



The mounting orientation is irrelvant. The pressure difference created by the weight of air is trivial in comparison with the pressuere difference created by a powerd fan.

Pulling air downwards would not "suck the heat from the RAM" because that is simply not how heat transfer works. In addition the airflow caused by the graphics fan, with the graphics card between it and teh RAM/CPU, is never going to have any seuch effect. But if it did do that, somehow cooling the RAM and other componentes, that would be a benefit, not a disadvantage. Provided only that there is a sifficient airflow through the VGA heatink, the air temperture will be kept suitably low and the VGA will be cooled.

You do not use the air inside the case to cool the hot exhaust air comming off the CPU. The effect of that can only be to heat up everyting inside the case, including the air being used to cool the CPU. The fan at the back of the case is there, in the position it is, precisely to ensure that as much of the hot air goes straight out of the back of the case as possible and does not re-circulate.

Nobody in this thread or in the Review at Tom's appears to have actually tested this. What guy "says no improvement"?

I am not aware of any aerodynamic theory that says the same fan will move a (significantly) different amount of air whichever direction it works in. The equations are symmetic, at least to the first approximation.

As I have already pointed out the tendency of hot air to rise is trivial in comparisin with eh effect of a powered fan. We are into quantitive effects here, not qualatitive.

The pressure difference accross the heatsink is zero until you switch on the fan. There is no significant pressure variation inside the case. This cooler is not vented to the outside of the case in either it's intake or it's outlet side. If it were, I agree that would be significant: but as it is, there is no difference in the power required to achieve a given airflow and hence no noise consideration.




Peter


 
there was a review on a simular design made by evercool on the switching of the fan. The evercool is also passive, ugh... these are all old reviews so finding them will be a pain in the butt. But it showed a digression as the fan was set up to pull instead of push.


Also this question can relate to why the VF900 cools better on a inverted board vs a regular board. Countless people have stated the VF900 cools better when the fins are up vs down. If you dont believe me ask people who own a LL V series and they'll all vouch that having the sink mounted on top cools better then on bottom.

*shurg* Whoever has one, test it out 😛 tell us which is better pull or push, and that will be the end of this topic. 😛
 
Hi,

I'm utterly prepared to believe that these is some difference, and that it's a consequence of all the little details of how the case is laid out, what CPU cooler is used, how the aiflow works, which side of the graphics card the cooler is attached etc.

Even the convection current of hot air rising will have some effect (however small), clearly: and if all of these effects happen to pull in the same direction there may well be an overall difference of several degrees.


What I do not accept, is the idea that there is any fundamantal reason, unrelated to the specific layout of a specific machine, why a pusher fan should be any better or worse than a sucker fan.


It is, for instance, quite possible that the reason this graphics card cooler works better with the fins on the top is that the air comming off the graphics card is exhausted more effectively by the rear case fan.


I think it's important to destinguish beteween effects that are general, and derive fom basic thermal or airflow theory, and effects that are consequences of the way a particular case is organized.


Peter
 
I have a VF900 but because it is placed on the same side of the PCB as the RAM - and I have sinks on the RAM - I prefer to have the fan push air down onto the card in order to take advantage of the RAM cooling as well, which would not be as effective if it was just pulling. Pushing causes more turbulence over the card itself and should get more airflow to the RAM heatsinks.
 
Originally posted by: pcy
Hi,

I'm utterly prepared to believe that these is some difference, and that it's a consequence of all the little details of how the case is laid out, what CPU cooler is used, how the aiflow works, which side of the graphics card the cooler is attached etc.

Even the convection current of hot air rising will have some effect (however small), clearly: and if all of these effects happen to pull in the same direction there may well be an overall difference of several degrees.


What I do not accept, is the idea that there is any fundamantal reason, unrelated to the specific layout of a specific machine, why a pusher fan should be any better or worse than a sucker fan.


It is, for instance, quite possible that the reason this graphics card cooler works better with the fins on the top is that the air comming off the graphics card is exhausted more effectively by the rear case fan.


I think it's important to destinguish beteween effects that are general, and derive fom basic thermal or airflow theory, and effects that are consequences of the way a particular case is organized.


Peter
Click to expand...

Static pressure?

If you were to take a cardboard box ,cut two parallel holes for the fan, then place the fan on one side, it should move the same amount of air regardless of whether it's pushing or pulling. However, when going through fins, the static pressure of the fan determines how well it moves air through an obstruction. IIRC, computer case fans have a higher positive static pressure. The negative static pressure is much lower, so the fan won't move as much air in a pull configuration. I could be totally wrong though.

 
Hi,


I agree there is a pressure change caused by the air flowing through the obstruction. But I don't see why it makes any difference which side the fan is.


Lets suppose the presure change is x and the air pressure inside the case is X.


Then if the fan is a "pusher" the fan input pressure is X and the fan output pressure is X + x; but if the fan is a "sucker" the input is X - x and the output is X.


Either way we have a pressure difference accross the heatsink of x and a pressure difference accross the fan of x also. That must be - the fan and heatsink are sitting inside the case which has sufficient space to allow free passage of air around it.


If x were a high proportion of X then there would be a an important difference between the two cases, because the "sucker" configuration wuold have lower pressure, lower density air flowing through the heatsink and fan. But in fact x is small compared to X and this effect is insignificant.


In consequence, I fail to see how either the heatsink or the fan can see any difference between the two cases.





Peter
 
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